According to new data from comScore, Facebook is dominating the U.S. display ad market. In Q3 2010, Facebook served 297 billion display ad impressions, which equates to 23% of the U.S. market for display ads. By way of comparison, its share was only 7% in the first quarter of 2009.

It’s interesting to note that even though Facebook serves up more display ads than any other company by far, it isn’t collecting a proportionate amount of ad dollars — the Wall Street Journal notes that it’s only securing 10% of display ad dollars. According to the WSJ, “Part of the reason for the gap between Facebook’s scale and the amount of money it makes from ads is that Facebook sells a good portion of its ads on a cost-per-click basis, where advertisers only pay if a consumer clicks on the ad. The more people that click, the more expensive the ad campaign will be.”

But it’s also true that advertisers are still trying to decide whether Facebook ads are worth the money, whether the platform is good for branding, and whether people are more likely to ignore ads they see there.

Facebook served up almost a quarter of the 1.3 trillion
online display ads in the third quarter, according to
ComScore data. But marketers are trying to figure out
how to value the ads on Facebook.

Facebook may not be raking in the dollars today, but it’s positioning itself as a big future earner — it’s a good bet that ad dollars will more closely match ad impressions in the not-to-distant future.